As conventional spectral modules,, those described in Patent Literatures 1 to 3 have been known, for example. Patent Literature 1 discloses a spectral module having a block-shaped support which is a biconvex lens, in which one convex surface of the support is provided with a spectroscopic unit such as a diffraction grating, while a photodetector such as a photodiode is disposed on the other convex surface side of the support.